From: Mike Rapoport <rppt@kernel.org>
To: Hyunmin Lee <hn.min.lee@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Uladzislau Rezki <urezki@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>,
Jeungwoo Yoo <casionwoo@gmail.com>,
Sangyun Kim <sangyun.kim@snu.ac.kr>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>
Subject: Re: [PATCH] replace BUG_ON to WARN_ON
Date: Tue, 31 Jan 2023 15:47:05 +0200 [thread overview]
Message-ID: <Y9kb2XUunZlgsu2z@kernel.org> (raw)
In-Reply-To: <20230131105629.GA1195431@min-iamroot>
On Tue, Jan 31, 2023 at 07:56:29PM +0900, Hyunmin Lee wrote:
> On Mon, Jan 30, 2023 at 12:14:04PM +0200, Mike Rapoport wrote:
> > Hi,
> >
> > On Fri, Jan 27, 2023 at 08:58:44PM +0900, Hyunmin Lee wrote:
> > > Replace unnacessary BUG_ON to WARN_ON. These BUG_ONs verify aruguments of a function. Thus, the WARN_ONs return an EINVAL error when their condition is true.
> >
> > Some users enable panic_on_warn, so for them WARN_ON will still crash a
> > machine.
> >
> > I think a simple if() will be sufficient.
> >
> Hi Mike,
>
> Thank you for your advice.
> Would you please give feedback about the below opinion?
> - Printing warning messages is helpful to inform what happened in the system to the users.
> - When a simple if() is used instead of WARN_ON, the if() should print a warning message.
> - The condition of the simple if() should also have unlikely() for optimization of system performance.
> - WARN_ON is a macro doing like thoes easily. It has a notifying function and unlikely optimization.
> - Eventhough WARN_ON will still crash like BUG_ON by some users who enable panic_on_warn, it is their intention. They should accept the crash by WARN_ON.
> - Therefore, using WARN_ON looks like natural and efficient.
As this is a validation of the function parameters, there is no need in
warning messages and if(unlikely()) will do. There is really no point in
WARN_ON() for something that's totally recoverable and very unlikely to
happen.
> Best,
> Hyunmin
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2023-01-31 13:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 11:58 [PATCH] replace BUG_ON to WARN_ON Hyunmin Lee
2023-01-27 15:03 ` Hyeonggon Yoo
2023-01-30 10:14 ` Mike Rapoport
2023-01-31 10:56 ` Hyunmin Lee
2023-01-31 13:47 ` Mike Rapoport [this message]
2023-02-01 10:03 ` Hyunmin Lee
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